Telescopic instrument for subjective determination of the refraction of the eye



()Ct. 13, 1931. w. THORNER 1,826,844 TELESCOPIC INSTRUMENT FOR SUBJECTIVE DETERMINATION OF THE REFRACTION OF THE EYE Filed July 22, 1929 E .J. h g I e I 6- k l ,,C

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Patented Oct. 13, 19 31 I V TELnscoPIc nvscmatnvrEmir. Foja' gamma-E DETEni/iInATIo c e, T E Y e I Application inea July- 22, T1929, Es ria m; 330,042, ma. German-y 11'11yj @25 ,.11 2s;

This invention relates to i device 1591;; the subjective determination ofthe re fractioniof the-eye by means of an adjustable (telescope s It is known for the purpose of subjectlve determination of the refrafction of theieye. to employ in place of a number of glasseswhi'ch are exchanged as required-atelescope, which is sharply adjusted to the -;"sight' test, and

from the graduationonwhichthe refraction may beread oil. j,

This method,howeverghashot proved to be, successful, asin looking through thetelescope the person-being examined isliable to gain the impression or" appreciateithat he is vlooking intoan optical instrument-and thusjquite involuntarily exert aparticular strain-Lon; the eyes in an endeavour t'o'adapt hisaccomm d tion.

. 7 I 5" V g It is the primaryaobject oftheipresen ,i'nvention, to overcome'-. the disadvantage ra' ferred to, and topr'ovide lan instrumentwhich will enable sight tests to be performed which are perfectly free from'el'l'br. Other objects and advantages o'fthe'invention will become apparent as the descriptionproceedsij h According to the invention it is proposed to employ a telescope asheretofore for determining'the refraction of the eye. 'In order, however, not to arouse in the'personbeing tested the impression that he is looking into an optical instrument, the whole passage of rays in the telescope is disposed in a plane ver tical to the direction of sight, so that the entering pupil and exit pupil in the direction of sight are quite close together. In this man ner theperson being examined has the im-. pression of merely looking through an ordi-' nary eyeglass, and thereforehas no reason'tofl. v o I A in trume "Fig; 1 is a vary his accommodation.

The disposal of the passage of therays in a plane vertical to the direction of sight is.

preferably so performed, that a glasscube is situated close to the eye, this cube being divided into two halves by an inclined plane.

The two sloped faces situated close together are silvered, the one reflecting towards the top and the other in a downwarddirection. The rays of light proceeding from the image are accordingly thus deflected .in an upward.

direction, and: with the assistance of four additional i fiaiaaPagans 1 alciii'sfed each"or he .:pa esmni gaedother; viz., the front, and'gre'ar ,lfafc'e s. ig ss u ndt pla eofih pupils ifi lL 8d $within the'telescope cylinder glasses orpri'sms may jbe.provided,.iwhich may each consist of v woj X pQ diia s,'wh 'bail fie e. .'r l-- ati ve rotationprovide in: the kn wn manner ;cylinder:.or prism combinations of differing strength-" 1 The i 1 wem e afl mia r R W GEBMNY.1755v a a P t within :the' plane: vertlcalito. the direction of sightvuntilthe same again return from below to the inclined refiectionface withintheglass cube, and then, but not. until then, pass to the eye. Within "the plane vertical? to the "tion of sight are situated the centre point of "the lenses belonging to the telescope; It. is

preferable "to employ a terrestrial, ,-tel escope having within the. same a plane which is conf jugated ,botlil t0. the I frontface 10f. the cube situated towards. the image 'asfwellias -tlie,v reaffacel Qtsituated towards the eye .The adjustment ofthe telescopeto different 1 .refractions is effected by. varying its length or aum *BEFBACTION or A in a direction parallel to the, connectingjline f eyeglass (the rear. face ,of'the} glas'sfjjciibe) the focal point of a fixed convex lens, so, that between the't'woeye's. Inthe'known manner 1 it =is;des irab1e;todispose the location of the' the telescope will require a uniformfvariatibl o its le g for veryafi trbpiafdi p r 'In vertical toflthe,same. ,The,rays of lightpr'oceeding from! the} image out i of, the direcp section the between'both'eyes, Fig. Q'being a sect on tion a areireflected in an upward direction ion the surface' h' oftheglasscube .0 andjpass,-,; 7

from thereto thereflection prism deflects, the rays laterally, V The sam mow "traverse the convex lens 6, in the lfocallpoint ;ofwhich is situatedzthe convex lens f, which in"minise fi telelese 9 the e e .41

of the person being tested. The convex lens f has the object of shortening the whole instrument. The rays then meet the convex lens h, in the focal point of which is situated the plane 7'), in which are located two relatively rotatable cylinder lenses. Intermediate h and is is the reflection prims i, which deflects the rays in a downward direction, and beyond 10 the reflection prism Z, which passes the rays again in the lateral direction until they meet the convex lens m. From this point the rays proceed to the convex lens 7%. and from there to the reflection prism 0, which again directs the same upwardson to the surface p,-which is situated in close proximity to the surface 6. Proceeding only from p are the rays passed to the eye 9 throughthe medium of the lens 7. The distance between the lenses 6 and h and also n and m may be varied simultaneously, thus enabling adjustment to be made for different refractions On the front faceof the glass cube 0 is also provided a Herschel prism q. I

' The whole arrangement is preferably constructed so as to be double, viz., for the left eyeand the righteye, and ismounted on a holder which is oscillatory in front of the face. The two single devices are connected with each other in such manner that their spacial relation in a horizontal direction may be varied in accordance with the distance between the pupils of the tested eyes.

A preclusion of the particular eye not being examined is preferably .eifected by inserting an opaque disc at some point of the passage of the rays in the telescope. p

As shown in Fig. 8, here are provided,suspended from an arm 1 and connected with each other by means of a'ball joint 8, the two lateral .arms 1; and u, the distancebetween these arms being capable of being adjusted in accordance with the distance between the eyes of the person being examined. The person under examination gazes into 0 through the view apertures. The length of the lateral arms is adjusted by rotationof the gear 1; until the person being tested is able to discern a sharp image, and the reading may be taken from the scale w. Thus, for example, in the drawings the right eye'has a hypermetropia amounting to +3 and the left eye a myopia amounting to 2 dioptres. The determination'of the astigmatism is performed by rotation of the gear '20, and the strength of the necessary cylinder glass is read ofl fromthe disc 41:. l

It will be understood that no restriction is made to the exact form of embodiment shown, and that various modifications may be made without departing from the spirit of the invention.

What I claim as new and desire to secure by Letters Patent is rotating said lens.

3. The invention as set forth in claim 1, wherein said optical system includes a pair of reflecting prisms having their reflecting surfaces contacting in a plane inclined to the line of sight and a second pair of reflecting prisms disposed in contact respectively with those surfacesv ofsaid first prisms which are inclined to the reflecting surfaces thereof and which lie in planes parallel to the line of sight, said second prisms having their reflecting surfaces lying in planes which intersect in a line parallel to the line of; sight.

4:. A device for the subjective determination of the refraction of the eye by determining the variation of the focus of a lens system disposed between the eye and an object necessary properly to observe the object, comprising a frame, a pair of focusing optical systems in said frame, constituting means for directing rays of-light from said object to both eyes respectively, in substantially closed paths lying in a plane substantially perpendicular to the line of sight and means for independentlyvarying the'focus of each of said systems. V

In testimony whereofQI aflix my signature. "WALTHER THORNER.

1. A device for thesubjectiVe determina- 7 tion of the eye by measuring the variation of 

